Hi jennyr265
I presume you are post-menopausal hence the daily Utro?
Progesterone does two things to the endometrium when taken continuously as part of HRT. At the right dose it prevents the oestrogen from having a stimulatory effect on the endometrium ( ie stops it growing), and if any lining has grown it converts it from proliferative ( growing) to secretory (preparing for fertilisation).
So - if the dose is right - the first will happen meaning when you stop the progesterone or the HRT completely - you won't bleed. If some lining has grown - then the progestogen converts it to secretory (structural changes take place) and then when you stop, the progesterone level drops which signals to the body that fertilisation has not taken place and any lining is shed.
Sometimes it takes a while for continuous progestogen to work on the whole endometrium to stop it growing - hence some women get intermittent bleeding and spotting.
Your oestrogen dose is very low so that is the explanation as you say. No lining to shed.
Some limited research showed that on low to medium doses of oestrogen (like you are taking), alternate day Utrogestan used vaginally was sufficient to thin the lining - so with your doc's consent or supervision this might be worth a try. Alternatively you could perhaps consider a longer cycle - giving a short withdrawal bleed every 6-7 weeks. My GP is happy for me to do this. It is only likely to work if you are post-menopausal though (longer cycle).
Are you using Tostran? I think that is quite a high dose of T for the amount of oestrogen you are taking and I presume you/gynae is monitoring this so you don't become too T dominant with associated androgenic effects?
Hurdity x